I'm getting into a lot of heavy CGI and Visual FX work for upcoming projects. Is there any benefit to keeping the Geforce GT 240 installed for the extra 1 GB of GPU? Or will it cause a bottleneck somewhere?

If there is a benefit, is 650W enough for both cards being that the recommended for the GTX 770 alone is 600W I believe?

Eric is completely correct, the GT 240 would not only possibly would cause you power supply problems but might even slightly slow preformance. I hope it is a good quality power supply as the cheap ones do not really deliver quality power under full load.

Regarding the 650 watt p/s, I suspect that you would be best served with at least 850 watts, especially if you plan on overclocking the cpu - and I definitely would for a 4930k.

Also regarding power supplies, you need to consider more than just the watt rating. Premiere Pro has an amazing way of using lots of simultaneous resources and this can really put a strain on your p/s. And if your p/s cannot handle the load, the results are not pretty.

Generally the good power supplies are more expensive and reviews like on Newegg can help you to quickly determine the quality.

I agree with the suggestion to ditch the GT 240, as well. You see, the GT 240 is of a much older GPU generation than your planned build's GTX 770 to begin with. And dual-GPU systems where one GPU is of a much older or different generation than the other will likely be much less stable than if both GPUs were of the same generation.

Next, the GT 240 is very slow by current standards, especially if your card has only DDR3 memory instead of the (G)DDR5 memory. (Remember, GT 240 cards with 1GB of memory could be had with DDR3 memory or GDDR5 memory, where the GDDR5 version has nearly double the memory bandwidth of the DDR3 version.) And that GPU has only 96 CUDA cores - a serious mismatch to your new system's CPU (in this case, the CPU must wait for the GPU to catch up, which is the exact opposite of what an overqualified GPU for a lesser-specced system would have performed). And even with GDDR5 memory, the GT 240 would have performed roughly equal to a GT 640 at best; the DDR3 version would have been as slow as or slower than a GT 630 (which is essentially a rebadged GT 440) with DDR3 memory.

Next, what is the exact make and model of the 650W power supply? You might end up with a PSU that cannot handle its full 650W rating in realistic operating conditions. Mediocre-quality ones can only handle about 500W while terrible-quality ones are only equivalent to roughly a 300W PSU. And don't rely solely on customer reviews on the Newegg site: Most of the reviews have absolutely no other PSU at all whatsoever to compare the reviewed product with, and most of those reviewers have systems that draw far less than those PSUs' maximum realistic power handling capabilities even at full load.

I had the GDDR5 version which did a decent job over the pasy years but as I get into more CGI work and VFX, it just doesnt cut it anymore. I dont know the brand of the PSU offhand but it isnt a cheap one. I'll have to look when I get home. The tech support from the custom PC company I purchased it from recommended it because of some type of failsafe it had installed or something. I'll let you know when I find out later. Thanks